Kntjt karl adolf christianson



UNITED STATES PATENT OFFICE.

KNUT KARL ADOLF CHRISTIANSON, OF STOCKHOLM, SWEDEN, ASSIGNOR TO..PETTERADOLF OS'IBERG, OF SAME PLACE.

PROCESS OF MANUFACTURING BlLLlARO-BALLS FROM IRON 0R STEEL.

sPECIFICATION forming part of Letters Patent No. 530,257, dated December4, 1894.

Applicationfiled May 29, 1894. Serial No. 512.918. (No specimens.)Patented in England August 24, 1893, No. 16,024.

To all whom it may concern.-

Be it known that I, KNUT KARL ADOLF CHRISTIANSON, a subject of theKingof Sweden and Norway, residing at No. 39 Handtverkarzatan,Stockholm, Sweden, have invented certain new and useful lmprovements inthe Manufacture of Billiard-Balls from Steel or Iron, (for which I haveobtained a patent in Great Britain, No. 16,024, dated August 24:,

1893;) and I do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same.

It is well known, that it becomes more and more difficult to procuregood billiard-balls, as ivory becomes more and more scarce, and attemptsto make billiardballs from other materials, such as hard wood, rubber,celluloid, and the like, have not proved successful.

I am aware from the United States Patent No. 275,923 of April 17, 1883,that attempts have been made to produce billiard-balls by solderingtogether segments of sheets of metal (steel), although apparentlywithout any practical success. It is evidently impossible to makebilliard-balls, equal to those made from ivory, in that way, as it isimpossible under those circumstances to accomplish either the necessaryuniformity as regards heaviness, depending upon the center of gravitycoinciding with the center of the sphere; or the perfect elasticitynecessary on every spot of the surface of the ball.

I have succeeded in making billiard-balls from iron or steel quite equalto those made from ivory, both as regards their elasticity and theircorrect evenness or uniform heaviness. As far as my experience goes, mybilliard-balls are moreover more durable than those made from ivory.Further, I can make them atthe same time equal in size and weight tothose of ivory.

I make the billiard-ball by casting it from steel or iron, hollow, andas nearly as possible of even thickness all around. Both the mold andthe core must be made with the utmost care so that the cast shell willbe free from blowholes, smooth, and of as regular a thickness aspossible. For the purpose of supporting the core during the operation ofcasting as well as for the purpose of removing the core afterward, theshell is cast with a small hole. When the ball is cast, the core iscarefully removed from the casting, and the hole is carefully filled upwith a plug from the same raw material and of about the same thicknessas the shell, the plug being carefully fixed preferably by means ofelectric welding. The ball is then turned perfectly round and wellpolished, so that the surface is smooth. Out of several hundred ballsalready made, I have not as yet found a single one, which after beingthus turned is of a truly uniform heaviness, without special adjustment.I have always found that the center of gravity does not coincide withthe center of the sphere. The ball is therefore examined on a horizontalpolished metallic plane, whereby the heavier half of the ball turns downand the lighter half turns up. The ball is then adjusted. If theirregularity is only extremely small, the adjustment may be effectedsimply by drilling in the center of the heavier half a very smallperforation, which if sufficiently small, does not injure the ball; orseveral small holes may be drilled regularly around the center of theheavier half. If the irregularity is greater, as is usual, theadjustment may be effected by drilling a hole in the center of thelighter half of the ball and filling the hole with a plug of justsufficient weight to shift the center of gravity so much that itcoincides with the center of the sphere. The adjustment however may beeffected by again turning the ball, for which purpose it is so placed inthe lathe that by taking away the least amount of material from thecenter of the lightest half, and the most from the center of theheaviest half, the center of gravity is made to coincide with the centerof the sphere. The two last mentioned methods of adjusting the ball,although they may appear difficult and unreliable, are in fact quiteeasy for a skillful workman after some practice. After turning theadjusted ball into its proper size and polishing it perfectly, it ishardened, if made from steel, and case-hardened if made from soft iron.

The characteristic properties of a billiard ball are: First, it must beperfectly spherical,

so as to roll easily and smoothly; second, it must be perfectly elastic,so as not to change its form permanently on striking against anotherball or other hard body; third, it must 5 be perfectly correct oruniform as regards its heaviness, depending upon the center of gravitycoinciding with the center of the sphere, so as to make the ball roll ina perfectly straight line, when rolling either quickly or 10 slowly, theword perfectly here indicating such a high degree of the respectivequalities, as is practically possible to obtain, or as is possessed byan ivory ball.

Iam well aware that spherical balls of metal I5 have previously beencast and used for different purposes, such as shot, bullets, cartridges,balls for seats in pumps, balls for bearings and the like; but none ofthese metallic balls, whether solid or hollow, has pos- 2o sessed suchqualities as are herein-above mentioned as essential for billiard-balls;viz., perfect elasticity and perfect uniformity as regards heaviness. ido not therefore claim as my invention any kind of hollow ball of steel25 or iron, neither any kind of hollow ball cast from steel or iron, butonly the process of producing by casting and subsequent operations, sucha hollow ball of steel or iron, which is both perfectly spherical, andthrough its hardness, perfectly elastic and perfectly ad- 0 justed sothat the center of gravity and the center of the ball coincide, all ofwhich qualities combined, make the ball a billiard-ball.

What I claim as my invention is- The process of manufacturing metallicbil- 3; liard balls, consisting in first casting them hollow and with asmall hole therein to aid in supporting the core during the casting,then removing the core and filling such hole with a metal plug, nextadjusting them per- 40 fectly and turning them perfectly round, andfinally hardening them to make them perfectly elastic, all substantiallyas set forth.

In testimony whereofI affix my signature in presence.of two witnesses.

KNUT KARL ADOLF GIIRISTIANSON.

Witnesses:

CARL Boos, A. MATTIESSON.

